Mount Hamilton not recommended for viewing Deep Impact

People interested in seeing what happens Sunday night when NASA's Deep Impact probe slams into Comet Tempel 1 will probably be better off sitting at their computers than gazing at the sky. One place they definitely should not be is atop Mount Hamilton, say police and astronomers at Lick Observatory. Parking at the observatory is very limited and there are no public facilities available for nighttime viewing.

Most experts think it is unlikely that viewers on the ground will see anything without powerful telescopes. The best images of the impact will be available from NASA on the Deep Impact web site: www.nasa.gov/mission_pages/deepimpact/main. This site will also feature a live webcast of the event's coverage on NASA TV.

"I will be following it at my computer, enjoying NASA's policy of putting it on the web as soon as possible," said Erik Asphaug, an associate professor of Earth sciences at UCSC and an expert on small planetary bodies such as comets and asteroids.

Amateur astronomers determined to view the event through their own telescopes will need to be in a dark location away from city lights, but Mount Hamilton offers no particular advantages and some potentially serious disadvantages, said Remington Stone, a research astronomer and director of operations at Lick Observatory.

The narrow and winding Mt. Hamilton Road (State Highway 130) becomes a safety hazard if too many spectators attempt to drive to the summit. Nighttime traffic jams have occurred on this road during other astronomical events, jeopardizing access for emergency vehicles and endangering pedestrians who have abandoned their cars.

"The top of Mount Hamilton is a long way to drive only to be turned away, and there is no advantage to being there as opposed to any other dark site," Stone said.

Furthermore, the lights from cars could interfere with astronomers' efforts to study the comet. Major telescopes around the world, including two of Lick Observatory's telescopes, will be trained on the comet to observe the impact.

"The comet surface brightness is quite low, and the amount of additional light from the impact could be anything, so we really do not want a lot of extra light on the ground that night," Stone said.

The impact is scheduled to take place at 10:52 p.m. Pacific Time on the night of Sunday, July 3. The Deep Impact spacecraft will deploy a 39-inch impactor into the path of the comet, which is about half the size of Manhattan Island. By observing the impact crater and how it develops, scientists hope to learn the basic structure and density of the comet.

"This is the first experiment conducted on any small planetary body--asteroid or comet--and it has the potential to revolutionize what we know," Asphaug said. "I'm one of those who don't think Tempel 1 is a ball of ice. I think the probe is going to hit something very porous, and this should be detectable in how (and whether) the crater forms."

Lick Observatory is an astronomical research facility operated by the University of California Observatories. Its administrative headquarters are on the UC Santa Cruz campus. The observatory's visitors' center is open to the public from 12:30 to 5 p.m. on weekdays and from 10 a.m. to 5 p.m. on weekends. For information, call (408) 274-5061.